Due to the way reddit is subdivided, it mostly keeps that toxicity quarantined to the groups that revel in it. For people who want to avoid it, it isn't particularly difficult to.

Well, people thought they could join FB to connect with their friends and family, but later on it turned to an insult-slinging platform, so hopefully the saner ones have left. As for reddit, I guess people are in the news and politics subreddits to actually fling shit at each other.

You can use reddit and completely avoid politics.

One could argue that the anonymity of Reddit in addition to the mods encourages a civil discussion

People aren't exactly nicer to each other when they're anonymous...

Sure, but it is a strange argument: morality is very sensitive to context, but in anonymous discussions lack most context and have to guess it.

So anonymous discussions are largely free of the restrictions imposed by the notions of common decency, so any civil discourse in unregulated media is a minor miracle.

The online disinhibition effect would argue the exact opposite.